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November 23, 2021
When bees get a taste for dead things: Meat-eating 'vulture bees' sport acidic guts
A little-known species of tropical bee has evolved an extra tooth for biting flesh and a gut that more closely resembles that of vultures rather than other bees.
Typically, bees don't eat meat. However, a species of stingless bee in the tropics has evolved the ability to do so, presumably due to intense competition for nectar.
"These are the only bees in the world that have evolved to use food sources not produced by plants, which is a pretty remarkable change in dietary habits," said UC Riverside entomologist Doug Yanega.
Honeybees, bumblebees, and stingless bees have guts that are colonized by the same five core microbes. "Unlike humans, whose guts change with every meal, most bee species have retained these same bacteria over roughly 80 million years of evolution," said Jessica Maccaro, a UCR entomology doctoral student.
Given their radical change in food choice, a team of UCR scientists wondered whether the vulture bees' gut bacteria differed from those of a typical vegetarian bee. They differed quite dramatically, according to a study the team published today in the American Society of Microbiologists' journal mBio.
To track these changes, the researchers went to Costa Rica, where these bees are known to reside. They set up baits—fresh pieces of raw chicken suspended from branches and smeared with petroleum jelly to deter ants.
The baits successfully attracted vulture bees and related species that opportunistically feed on meat for their protein. Normally, stingless bees have baskets on their hind legs for collecting pollen. However, the team observed carrion-feeding bees using those same structures to collect the bait. "They had little chicken baskets," said Quinn McFrederick, a UCR entomologist.
For comparison, the team also collected stingless bees that feed both on meat and flowers, and some that feed only on pollen. On analyzing the microbiomes of all three bee types, they found the most extreme changes among exclusive meat-feeders.
Why Did the Bee Eat the Chicken? Symbiont Gain, Loss, and Retention in the Vulture Bee Microbiome, mBio (DOI: 10.1128/mBio.02317-21 [doi.org])